Carburetor fuel bowl supply and drain system



United States Patent Inventor Jack B. King Royal Oak, Michigan Appl. No.755,959

Filed Aug. 28, 1968 Patented Oct. 20, 1970 Assignee General MotorsCorporation Detroit, Michigan a corporation of Delaware CARBURETOR FUELBOWL SUPPLY AND DRAHN SYSTEM 2 Claims, 1 Drawing Fig.

US. Cl....'. 123/136,

123/ 139 int. Cl ,.F02m 37/10 Field of Search 123/136,

[56] References Cited UNITED STATES PATENTS 2,293,884 8/1942 Boyce123/139 2,855,949 10/1958 Sterner eta 137/414 3,385,316 5/1968 Couffer137/414 Primary ExaminerLaurence M. Goodridge Alrorneys-Charles K.Veenstra and Jean L, Carpenter ABSTRACT: A carburetor float bowl has afloat-controlled inlet and a bottom opening both connected through aflow control chamber to a centrifugal type pump located in a fuel supplytank below the bowl, the chamber having a pressureresponsive diaphragmpermitting rapid filling of the bowl through the bottom opening when thepump is operating and drainage ofthe bowl when the pump is inoperative.

Patented Oct. 20, 1970 3,534,721

INVENTOR.

flTTOR/VEY CARBURETOR FUEL BOWL SUPPLY AND DRAIN SYSTEM BAUKGROUNI) OFTHE INVENTION l.Field olthc Invention This invention relates to fuelsupply supply systems for engines and the like, and particularly to thefilling of a carburetor float bowl from a fuel tank located at a lowerlevel and drainage of the fuel back to the tank when the supply pump isinoperative. Such emptying of the float bowl is especially desirableimmediately after an engine shutdown in order to avoid the highevaporation of fuel therein which might otherwise accompany increasedheat absorption from the engine.

2.Description of the Prior Art While it is old in the prior art toprovide for drainage of the fuel remaining in the carburetor float bowlwhen the engine is shutdown, my invention is believed to have advantagesover such prior arrangements in that it enables minimizing both the sizeof the float bowl and the capacity of the supply pump. Thus there aresuch prior systems as shown in U.S. Pat. Nos. 2,965,086 and 3,048,157 toGregory et al., for example, wherein return flow from the bowl back tothe tank occurs continuously during pump operation. Although they effectthe desired emptying of the bowl when the engine and pump areinoperative, the pump must be provided with the additional deliverycapacity to make up for the return flow and it affords no reduction fromthe usual float bowl capacity.

Another scheme which has been proposed for emptying of the float bowl isshown. for example, in U.S. Pat. Nos. 3,256,870 to Walker and 3,277,877to Rosenberg wherein a separate diaphragm type or plunger-type pump isemployed to withdraw the fuel into a storage reservoir upon engineshutdown. Still another alternative is represented by U.S. Pat. No.2,293,884 to Boyce in which emptying of the bowl is accommodated by adrain passage under the control of a check valve which is normally heldclosed by supply pump pressure when the engine is operating.

SUMMARY OF THE INVENTION My invention provides for the desired drainingof the float bowl upon engine shutdown in a very simple and inexpensivemanner through the use of a flow-control valve which is inserted betweenthe pump and the inlet and bottom drain openings of the float bowl. Thearrangement is such that the float-controlled inlet valve in the bowlacts only to provide a pressure signal to the control valve which, inturn, allows flow to the bowl through the bottom opening for rapidfilling thereof during pump operation, as well as drainage of the bowlthrough the same bottom opening when the pump is inoperative as duringan engine shutdown. As a result, rapid filling of the bowl upon enginestartup is not dependent upon the flow capacity of the float controlledinlet, and hence both the size of the float bowl and itsfloat-controlled valve may be made much smaller than is conventional.Also, by using a centrifugal or other nonregenerative type supply pumpwhich accommodates reverse flow therethrough when the pump isinoperative, the required capacity of the supply pump is less than thatfor other such systems which require either a separate bypass around thepump, continuous return flow from the float bowl, or filling of thefloat bowl only through the float-controlled inlet.

Other objects and advantages of the invention will be apparent from thefollowing description of the preferred embodiment thereof, havingreference to the drawing which schematically shows portions of acarburetor float bowl, fuel supply tank and pump and the flow-controlvalve connected between the float bowl and the pump.

Description of the Preferred Embodiment A carburetor float bowl isindicated at 1, having therein the usual pivoted float 2 arranged toraise an inlet valve 3 up wardly from its position shown to close theinlet 4 to the bowl when the level 5 of the fuel therein reaches apredetermined height. It will be understood that fuel is withdrawn fromthe float bowl via one or more passages not shown as required by theoperation of the engine with which the carburetor is associated. Locatedat a level below the float howl l is a fuel supply tank (1 containingfuel to be transferred to the float bowl as necessary to maintain thepredetermined level therein as established by the float 2. Within thetank is shown a strainer or filter 7 through which the fuel passes to apump 8 which serves to transfer the fuel to the float bowl 1. Theparticular pump 8 illustrated is arranged within the tank 6, although itwill be appreciated that the pump may be located externally of the tankat a suitable point in the delivery conduit 9, provided, of course, thatthe pump be sufficiently selfpriming to insure adequate delivery of fuelfrom the tank to the conduit 9. Also, the particular pump 8 illustratedis of the centrifugal type comprising a rotary impeller 10 driven by anelectric motor 11. Such pump has advantageous employment in my inventionby reason of the fact that the impeller 10 accommodates reverse flow offuel back to the tank when the pump is not operating. Othernonregenerative-type pumps may be used with similar advantage, andalternatively a diaphragm or plunger-type pump of greater capacity mightbe substituted therefor incorporating a suitable bypass around the pumpelement to accommodate such reverse flow during shutdown.

Fuel flow to the float bowl inlet 4 is continued through a conduit 12which is connected to the upper end of the conduit 9 by a flow-controlchamber 13. This chamber is also conneeted with a bottom opening l4 inthe float bowl by a short conduit 15, and this conduit communicates witha passage 16 terminating with a port l7 within the chamber [3. Normallyclosing the port 17 and partitioning the chamber 13 into portions 13 and13" is a valve in the form ofa flexible diaphragm 118. This diaphragmmay be made of soft synthetic rubber or other elastic material and abypass is provided laterally of the port 17 in the form of one or moreapertures in the diaphragm, of which one such aperture is shown at 19. Aspring (not shown) may be added to bias the diaphragm toward the port,but it should not be required if the diaphragm is installed under slighttension so as to utilize its own resilience in biasing itself to theposition shown.

During operation of the pump 8 fuel is delivered from the tank throughthe conduit 9 to the chamber portion 13" from which it flows through theaperture or apertures 19 into the chamber portion 13'. If the pump hascommenced operation while the float-controlled inlet valve 3 is in openposition (as shown) fuel from the chamber 13' thence flows through theconduit 12 and bowl inlet 4 into the float bowl 1, and continues to soflow until the inlet valve 3 closes under the action of the float 2 inresponse to the rising level of fuel in the bowl. During such period ofoperation a pressure drop occurs in the fuel passing through theaperture 19 due to its flow capacity being less than that delivered bythe pump to the chamber 13, with the result that the greater pressureexisting in the chamber portion 13" acts to move the diaphragm 18 to theleft of its position shown, uncovering the port 17 and allowing rapidfilling of the float bowl via the passage 16, conduit 15 and bottomopening 14 in the bowl. The capacity for this latter flow is greaterthan that accommodated by the bowl inlet 4 and, in fact, the inlet 4 maybe made relatively small since the rate of filling of the bowl is notdependent thereon but is dependent upon the greater flow capacity of thepassage means 14-17. Upon the inlet valve 3 closing the inlet 4 when thedesired predetermined level of the fuel in the bowl has been reached,further flow through the aperture 19 ceases with the result thatpressures in the chamber portions 13' and 13" are then equalized. Thearea of diaphragm l8 exposed to chamber 13 is greater than the areaexposed to chamber 13" with the result that a greater force is exertedon diaphragm 18 by the pressure present in chamber 13'. Diaphragm 18 isthus returned to the position shown, closing the port 17 and blockingfurther supply of fluid to the float bowl. As fuel is withdrawn from thebowl in supplying the engine with which it is associated and opening ofthe inlet valve 3 again occurs. the flow resumes via conduit 12 andpassage means l4-l5 to maintain the required fuel level in the bowl.

Upon stopping the operation of the fuel pump, as during an engineshutdown. the fuel pressure in the passage 16 acts against the diaphragm18 to uncover the port 17, allowing the fuel to drain back to the tankvia the passage means 14 -l7 chamber 13. conduit 9 and pump impeller 10.

It will be appreciated that minor changes in the parts and theirarrangement may be made without departing from the spirit and scope ofmy invention as defined in the following claims.

lclaim:

l. The combination of a carburetor fuel bowl having an inlet and abottom opening, a fuel tank located at a level below said bottomopening, a fuel pump operative to transfer fuel from said tank to saidbowl. means defining a flow-control chamber having a port openingcentrally therefrom and an annular portion surrounding said port and afurther portion, a delivery conduit connecting said annular portion ofsaid chamber and said pump, a fuel conduit connecting said furtherportion of said chamber and said inlet of said fuel bowl, a fuel passageconnecting said port and said bottom opening of said fuel bowl, aflexible pressure responsive diaphragm partitioning said chamber toseparate said annular portion from said further portion and overlyingsaid port to control fuel flow between said annular portion and saidfuel passage, said diaphragm having an aperture connecting said annularportion of said chamber and said further portion of said chamber, saidaperture having less capacity for fuel flow than said pump and deliveryconduit whereby a pressure differential is created across said diaphragmto move said diaphragm away from said port and permit fuel flow fromsaid annular portion of said chamber through said port to said bottomopening of said bowl when said pump is operative and said inlet is open.an inlet valve controlling said inlet, and a fuel level responsive floatin said bowl connected to said valve and causing said valve to closesaid inlet when the fuel in said bowl rises to a predetermined levelwhereby the pressure in said further portion of said chamber isincreased to cause said diaphragm to move toward said port and preventfuel flow from said annular portion of said cham be rthrough said portto said bowl then when said pump is operative and said inlet is closed,said pump accommodating reverse flow of fuel from said annular portionof said chamber to said tank when inoperative whereby a pressuredifferential is created across said diaphragm by the static head of fuelin said bowl above said bottom opening to cause said diaphragm to moveaway from said port and permit fuel flow from said bottom opening ofsaid bowl through said port to said annular chamber when said pump isinoperative.

2. The invention of claim 1 wherein said port, said fuel passage, andsaid bottom opening of said bowl have a greater capacity for fuel flowthan said fuel conduit and said inlet of said bowl.

